import math
xa,ya,xb,yb=map(float, input().split())
print("{0:.8f}".format(math.sqrt( (xa-xb)**2 + (ya-yb)**2 ))) import math math xa,ya,xb,yb=map(float, input().split()) xa map(float, input().split()) map float input().split() ().split () input split ya xb yb print("{0:.8f}".format(math.sqrt( (xa-xb)**2 + (ya-yb)**2 ))) print "{0:.8f}".format(math.sqrt( (xa-xb)**2 + (ya-yb)**2 )) "{0:.8f}".format "{0:.8f}" format math.sqrt( (xa-xb)**2 + (ya-yb)**2 ) math.sqrt math sqrt (xa-xb)**2 + (ya-yb)**2 (xa-xb)**2 xa-xb xa xb 2 (ya-yb)**2 ya-yb ya yb 2 xa,ya,xb,yb=map(float, input().split()) map(float, input().split()) xa ya,xb,yb=map(float, input().split()) map(float, input().split()) ya yb=map(float, input().split()) map(float, input().split()) yb xb,yb=map(float, input().split()) map(float, input().split()) xb
import math
xa,ya,xb,yb=map(float, input().split())
print("{0:.8f}".format(math.sqrt( (xa-xb)**2 + (ya-yb)**2 )))